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Dec. 11, 1928.- I

W. J. WINNINGHOFF THERMOSTATIC ELECTRIC SWITCH Filed Nov. 10, 1923 2 Sheets- Sheet 1 THERMOSTA'TIC ELECTRIC swI'rcI Filed Nov. 10. 1936 2 sheets sheet 2 INVENTOR Patented Dec. 11, 1928;

UNITED STATES 1,695,261 PATENT OFFICE.

WILFORD J. WINNINGHOFF,"- OF EAST ORANGE, NEW JERSEY, ASSIGNOR T0 COOPER HEWITT ELECTRIC COMBANY. OF HOBOKEN, NEW JERSEY, A CORPORATION OF NEW JERSEY.

THERMOSTATIC ELECTRIC SWITCH.

Application filed November 10, 1923. Serial No. 673,900.

My present invention relates to switching apparatus for electrically heated appliances and especially for use with electrical flat irons, and provides means for disconnecting the appliance on the attainment therein of temperatures which have become dangerously or excessively high.

A large percentage of fire loss today is caused by electric fiat irons which left unattended reach excessive temperatures result-.

ing in the ignition of tables or stands on which they are left or pieces of furniture or the floor on which they may have fallen and the ultimate destruction of property amounta ing to enormous values.

Numerous safety appliances are on market as part of electri cal iron mechanisms or. as auxiliary apparatus thereto whose intended purpose is to prevent fires whch might be caused through excessive temperatures reached in the irons which, however, have proven ineffective.

It is a purpose of my invention to provide means for opening a circuit which supplies electrically heated fiat irons and the like automatically on the attainment therein of abnormal or excessive temperatures.

It is another object of my invention to provide means for cutting off such current au toma-tically at such high temperatures and leaving it off until turned on again by an attendant. I have shown my invention in the accompanying drawing which forins part of this application, and which showsin Fig. 1, a diagrammatic representation of the application of my invention to aheater circuit;

Fig. 2, the application of my invention to electrically heated fiat irons is diagrammatically shown; I

Fig. 3, a diagrammaticrepresentation of a system similar to that ofFig. 1 but with a resistance in series with the mercury short circuiting switch;

Fig. 4, a similar diagram in which part of the heater resistance is used as the resistance of Fig. 3 in series with the shortcircuitv ing switch.

The electrical resistance heater 2 is connected to the supply mains 6 and 7 through leads 8 and 9. Across these leads and in shunt to said resistance heater is the thermostatic switch 1, connected to leads 8 and 9 by leads 10 and 11, respectively. The said thermostatic switch 1 is a sealed vertical tubular envelope of glass having the terminal elec-' trode 12 sealed through the wall thereof near 1ts bottom and the terminal electrode 14 sealed through its wall near the top thereof. Within the said envelope is the body 13 of mercury contacting with said electrode 12 and normally at a level below the electrode 14. The quantity of mercury and the level thereof with respect to said electrode 14 at normal temperature or temperatures which are considered below the dangerous point is predetermined so that the expansion of the mercury attending increases of temperature will bring the mercury to such a level that said mercury will contact with said electrode 14 and establish electrical connection therewith when such temperatures'become abnormal or dangerously excessive. In one of the leads from the supply mains between said main and the mercury switch 1 is connected the circuit breaker 3+4, .and the suitable switch 5 is provided in the circuit.

In Figurefl is shown flat iron 15 having within body'16 thereof the electric heating element 2 connected by leads 8 and 9 to the or other suitable equivalents,'and a corre sponding part to the source of electric current and the iron used in the usual way. The iron beingcold the level of mercury in switch 1 is below electrode 14 and the circuit through said switch is open. The contactor 4 of circuit' breaker 34 is, of course, closed. Should the iron reach a temperature during the use thereof which is above a predetermined point the mercury 13 will expand sufliciently to close the circuit through switch 1 thereby short-circuiting the electric heater 2 and shunting circuit breaker 3-4 across the supply mains 6 and 7. Abnormal current then assing through solenoid '3. of said circuit reaker the contactor 4 thereof will be opened and left open until manually closed by the operator through handle 19 as diagrammatically shown in Figure 2. Should the contactor 4 be again closed before normal temperature is approached in the iron and mercury 13 has receded through contact 14, solenoid 3 will continue to function to open contactor 4 until such temperature has been approached and the level of mercury 13 has receded from electrode 14 to open the circuit through switch 1. Likewise should the iron.

be left or forgotten with the source of current connected to, the heater the switch 1 and solenoid 3 will function to operate to open contactor 4: upon the reaching of abnormal or dangerous temperature in the manner described above.

As shown in Fig. 3 I employ in circuits where there is possibility of a fuse blowing out before the circuit breaker 3-4 operates to open the circuit, a resistance 15 in series with the switch 1 between leads 8 and 9. This resistance is used to limit the current passing through the circuit shorted 'on the closing of switch 1 to the current necessary for the operation of the circuit breaker. And as shown in Fig. 4 where conditions require or allow I use a part of the heater resistance as the resistance for limiting the current through switch 1, the lead-10 being connected to a point intermediate the ends of the heater resistance 2.

M Vhile I have shown the circuit breaker as opening one side of the circuit main I use when required a breaker for opening both sides of the maincircuit and operated by a coil or coils in'either or both of the lines. Such an arrangement is made by providing the armature of circuit breaker 3-4 with mechanical connection with a switch in main 8 of Figure 1 for the opening thereof by said armature simultaneously with the opening of switch 4.

I claim: I 1. ,In an electric heater c1rcu1t,1n combination, an electric resistance heater, 9. temperature closed switch in shunt with said heater, and a circuit breaker in a lead to such heater and switch actuated by the flow of abnormal current therethrou h.

2. In an electric heater circuit, in combination, an electric heating means, a thermostatic mercury switch in shunt with said heater, said switch being open at normal temperatures and closed at predetermined higher temperatures, leads to said heater and switch, and a current actuated circuit breaker in one of said leads actuated by the fiow of abnormal current therethrough.

3. In an electric fiat iron, in combination, an electric heater in the body of said iron, a thermostatic switch in close proximity to said heater and electrically shunted across said heater, leads through said heater and switch and terminals therefor, and means in one of a said leads for opening a circuit therethrou'gh upon the shunting of said heater and said thermostatic switch.

4. In an electric flat iron, in combination, an electric heater for said fiat iron, a thermostatic mercury switch positioned near said heater and electrically shunted there across, leads to said switch and heater, and a current controlled circuit breaker in one of said leads actuated by abnormal increases of current flow therethrough. i

5. In an electric heater circuit, in combination, an electric resistance heater, a tempera.-

ture closed switch in shunt with said heater and a circuit breaker in a lead to said heater and switch said circuit breaker comprising a solenoid and a contactor which are in series with each other in the lead in which they are connected.

. Signed at Hoboken, in the county of Hudson and State of NewJersey, this 9th day of November, A. D. 1923.

WILFORD J. WINNINGHOFF. 

